This is a non-provisional application based on provisional application Ser. No. 60/296,017, filed Jun. 5, 2001, for which priority is claimed.
This invention relates to methods and apparatus for the precise dispensing of liquid and fluid ingredients for mixtures and combinations, and more particularly, to precision dispensing in such industries as the paint (and coatings), ink, and cosmetic industries.
Precision dispensing (PD), in its simplest form, is accurately measuring something that resides in one container and transferring it to another. PD is commonly used in the paint and coatings industry, in which color combinations are created to form final paint products.
Paint products are typically derived from combinations of base colors and high-concentrate colorants. The base colors comprise nearly 80-90% of the total formula, while colorants commonly consist of the final 10-20%. The colorants are concentrated in that very small amounts significantly change the final color result. As an example, a gallon container of pure white paint is turned grey with a few drops of concentrated black.
Consumers encounter a basic form of dispensing when they buy paints for the home. If a consumer decided to paint a sunroom yellow, to select the specific yellow color, the consumer would typically choose the color from paint chips available at hardware, home improvement, and paint supply stores. If xe2x80x9cSunrise Yellowxe2x80x9d were to be selected, the consumer would hand the xe2x80x9cSunrise Yellowxe2x80x9d paint chip to a store clerk to have a gallon or a few gallons mixed, or name the color from the chip. The clerk would typically take a gallon of paint from a shelf, with the gallon having a xe2x80x9cbase colorantxe2x80x9d inside. The gallon container would be almost completely filled. He or she would consult a guide to find the formula for xe2x80x9cSunrise Yellow,xe2x80x9d open the container, and put the open gallon of base colorant in a dispensing machine, to add the colorants. Following the formula, the clerk would pull some levers on a dispense head, and by doing that, add the necessary colorants to the paint base. The gallon would be resealed and mixed in another machine. This would be done for each gallon. To finish the sale, the clerk would remove the lid, spread a little fresh paint on the chip, blow dry the paint, and ask for customer approval.
The request for approval is significant. By experience, some consumers think the request for approval is insignificant, because they assume the paint in the container they purchase will match the paint chip, since the dispensing and mixing was done by machine. Nevertheless, looking closer at the process, the xe2x80x9cSunrise Yellowxe2x80x9d the consumer receives and the xe2x80x9cSunrise Yellowxe2x80x9d that the last customer of this color received may be far from the same. The formula for xe2x80x9cSunrise Yellowxe2x80x9d might consist of 3.5 Kg of Titanium Dioxide (a common white base), 0.5 Kg Biocide, 0.5 gr. Red Oxide, 4 gr. Yellow, and 0.25 gr. Green. If, as a result of lack of precision in the dispensing machine or the store clerk""s use of it, the clerk dispensed 3 gr. Yellow, and 0.5 gr. Green, instead of 4 gr. Yellow and 0.25 gr. Green, the color could vary significantly from the paint chip, although not vary much from the formula. The typical machine currently used to produce the paint at the typical home improvement store is only accurate to about 1 gram. As a result, in some instances, the color differences from one gallon of paint to the next, of the xe2x80x9csame color,xe2x80x9d can be quite severe.
This situationxe2x80x94consumer purchase of paints dispensed gallon by gallonxe2x80x94is a very basic one that uses very simple dispensing technology. In most instances, people do not question the results because the color matching is adequate to most untrained eyes, and people do not really understand the basic principles involved in producing their paints. For these reasons the consumer paint store machines do not require much sophistication.
Other situations require much more. For example, in the automobile industry, a gallon of paint will cost on average $80-$90 per gallon. There, the paint specification (spec) is looked at much more closely. In fact the auto manufacturers such as GM, Honda, and Chrysler have very high standards in place that paint manufacturers are required to hold. You can imagine 4000 gallons of paint on a Corvette production line that does not pass spec at a cost of over $320,000; someone might be out of a job at the end of the day. Auto manufacturers can tell if the paint color is correct by a device called a spectrophotometer. This light-measuring instrument uses a laser to detect the color reflection from paint, and can determine exactly what the formulation of the paint is by the spectrum of light it reflects.
In situations that need PD and better technology to dispense paint, two methods are available today: Gravimetric Dispensing (GD), and Volumetric Dispensing (VD). Each will be described in detail in the following sections of this specification. Briefly, gravimetric dispensing relies on weight scales and measures quantities by their weights. Volumetric dispensing relies on volumes and measures quantities by their size. Both methods have numerous deficiencies that slow their speed and decrease their accuracy. GD has deficiencies in dispense valve actuation, dispensing time, accurate reporting, scale cost, effect of vibration and wind currents, pump wear and cost, air fluctuation, and multiple scale cost. Manual VD (MVD) is not really precision dispensing. Automatic VD (AVD) has deficiencies in accuracy, over time, dispense size, dispense speed, and viscosity limitations.
In a principal aspect, the invention is an automatic hybrid volumetric method of dispensing (HVD) that improves on gravimetric dispensing and volumetric dispensing. The method dispenses ingredients for a mixture, according to pre-selected formulations, utilizing a supply of the fluid ingredients, an ingredient container, a power-driven plunger in the ingredient container, a mixture container, and a calibration weight scale. The plunger is movable to expel fluid in the ingredient container. The method includes several steps. The ingredient container is connected to the supply to receive a first ingredient in the ingredient container. The ingredient container is connected to the mixture container for the mixture container to receive ingredient expelled from the ingredient container by movement of the plunger. The method is calibrated by powering the plunger to move in the ingredient container a controlled distance, to expel ingredient to the mixture container, while weighing the increase in the weight of the mixture container, resulting in a calculated rate of weight dispensed per increment of movement of the plunger. The ingredients are dispensed according to the formulations in the weight amounts required by the formulations from the supply through the ingredient container to the mixture container, through calibrated movements of the plunger in the ingredient container.